Regional variation in the cheetah (Acinonyx jubatus) revisited: Morphology of wild and captive populations

The cheetah (Acinonyx jubatus) is listed as a vulnerable species by the International union for the conservation of nature (IUCN), including two critically endangered subspecies, the Saharan cheetah, and the Iranian cheetah, so it is imperative that we understand variation in cheetah morphology to make good decisions regarding the conservation of this species. Here, we aim to determine whether northeastern African cheetahs have smaller body sizes than southern African cheetahs. This study also adds to our knowledge of cheetah morphology from two cheetah populations that do not yet have comprehensive published data: Kenya, and northeastern Africa, including captive individuals. We calculated means and standard deviations on cranial and body measurements of live or in few cases, freshly dead, cheetahs from the aforementioned populations, plus previously published data on Namibian and Botswanan cheetahs and compared them to one another using multivariate analysis of variance. Results show that northeastern African cheetahs have smaller body sizes than southern and eastern African populations. We also found that captive cheetahs retain the morphological characteristics of their ancestral population- captive cheetahs from southern Africa have similar body sizes to wild southern African cheetahs and larger body sizes than captives from northeastern Africa. Other analyses regarding cheetah growth agree with previous studies on Namibian and Botswanan cheetah populations rates. As such, this study can serve as a baseline for the care of captive cheetah populations to maintain healthy weights and body proportions.     

Influence of Oxides on the Stress Evolution and Reversibility during SnOx Conversion and Li‐Sn Alloying Reactions

The effect of varying the oxygen content in Sn and SnO_x films during potential dependent SnO_x conversion reactions and Li_ySn alloying relevant to Li ion battery anodes is examined. For metallic Sn films, the stresses and stability of the films are controlled by Li alloying reactions. Small, non‐contacting separated Sn particles exhibit higher electrochemical stability relative to more continuous polycrystalline films with larger particles. Metallic Sn particles develop tensile stress during Li_ySn de‐alloying as porous structures are formed. The amount of stress associated with lithiation and delithiation of well‐separated metallic particles decreases as a porous, easy to lithiate, material forms with cycling. During the lithiation of oxides, conversion reactions (SnO_x → Sn) and the lithiation of the metallic Sn control the stress responses of the films, leading to highly potential‐dependent stress development. In particular, evidence for a multistep electrochemical mechanism, in which partially reversible lithiation of the oxygen‐containing phases is conjoined with a fully reversible lithiation of the metallic phases of the Sn, is found. The electrochemical stress analysis provides new insight into these mechanisms and delineates the extent of the reversibility of lithiation and conversion reactions of oxides.     

Diurnal and seasonal variations in photosynthetic and morphological traits of the tree ferns Dicksonia antarctica (Dicksoniaceae) and Cyathea australis (Cyatheaceae) in wet sclerophyll forests of Australia

Steady state and dynamic responses of two tree fern species of contrasting origins, Dicksonia antarctica (of Gondwanan origin) and Cyathea australis (Pan-tropical), were studied over two consecutive years under field conditions in a wet sclerophyll forest of south-east Australia. Irrespective of their different origins, there were no significant differences in photosynthetic performance between the two species. Growth irradiance and leaf temperature, but not plant water status, was significantly related to photosynthetic and morphological traits. At a common leaf temperature, maximum light-use efficiency of photosystem II (F_v/F_m) was significantly lower in winter than in summer, suggesting some limitation to PSII efficiency potentially associated with cold winter mornings. Both species displayed seasonal acclimation in a number of measured photosynthetic parameters and frond traits (i.e. F_v/F_m, A_sat, g_s, N_A, total chlorophyll, SLA). Acclimation of stomatal density to spatial variation in growth irradiance seemed limited in both species, although stomatal pattern differed between species. Because there were no significant differences between the two species in photosynthetic parameters, both species can be described by common carbon gain and water use models at the leaf scale.     

Lipopolysaccharides of three classes of supersensitive mutants of Salmonella typhimurium

Abstract Cresyl violet acetate was found to be an appropriate redox-indicator dye in anaerobic culture media with low redox potentials. Low redox potentials ( E '_h−250 to −300 mV) in media were obtained by addition of dithiothreitol (DTT). DTT and cresyl violet acetate in media did not influence the total number of anaerobes cultured from human feces.     

Bacterial colony screening with a Streptomyces DNA probe

Restriction fragments of 1.5 kb-3.5 kb length were selected from a SalI digest of Streptomyces coriofaciens ISP5485 DNA. After radiolabelling, these fragments were used as a molecular probe. A number of actinomycetes was screened in colony hybridization. Streptomyces and Streptoverticillium strains were recognized by the probe and the hybridization sensitivity was high with isolated DNA.     

Method of color measurements of the elements of color in gastropods shell

The method of the accurate determination of the shell color of gastropods has been studied with the example of the gastropod Littorina obtusata. The suggested method is based on using the system of MKO RGB color coordinates and makes it possible to conduct measurements of both color as a whole and the color of the individual elements of the shell picture.     

Neural correlates of blood flow measured by ultrasound

1. Download : Download high-res image (164KB)
2. Download : Download full-size image

     

Effects of housing and management conditions on teat cleanliness of dairy cows in cubicle systems taking into account body dimensions of the cows

Dirty udders and teats result in a higher workload in terms of cleaning before milking and may constitute a risk for udder health. The aim of this prevalence study on 23 farms with very low within-farm variation in cubicle measures and other cubicle characteristics was to identify potentially influencing housing and management factors concerning teat and teat tip soiling. Information about udder soiling, housing and management was collected through direct recording and farmers’ interviews. Height at withers, shoulder width and diagonal body length were measured in 79% to 100% of the cows in each herd. On the basis of the 25% largest animals, compliance with recommendations for cubicle measures was calculated, which was generally rather low. Stepwise regression was used to find predictors for the percentage of dirty teats and of dirty teat tips. The final model on dirty teats explained 58.5% of the variance and contained four factors (F = 6.34, P = 0.0023). Less soiled teats were found on farms that conducted teat dipping after milking (t = −3.21, P = 0.0048), had increased daily cubicle maintenance time (t = −2.58, P = 0.0187), deep-bedded cubicles (t = −2.42, P = 0.0265) and decreasing compliance concerning cubicle length (t = 2.33, P = 0.0317). The final model on teat tip soiling explained 46.0% of the variance and contained three factors (F = 5.39, P = 0.0075). Less soiled teat tips were associated with increasing height of bedding material (t = −2.89, P = 0.0094) and decreasing compliance concerning resting length (t = 2.12, P = 0.0470). Difficult to explain was the association found between increased passage soiling and decreased teat tip dirtiness (t = −1.86, P = 0.0790). Thus, even under relatively restrictive cubicle conditions, a certain increase in teat and teat tip soiling was found with increasing cubicle length. However, at the same time, measures relating to good management may positively affect teat and teat tip cleanliness. In addition, deep-bedded cubicles yielded advantages in this regard. Both regression models for teat and teat tip cleanliness contained similar but not identical predictive variables. This indicates that dirtiness of each particular area may originate from slightly different though related causes. The low correlations found between udder, teat and teat tip cleanliness should be considered in future studies.